I suggest you get price quotes from:
http://www.fedex.com/us/international/shipping-to-north-america/index.html
www.dhl.com
Your speakers need to be packed correctly to ensure safe delivery in Germany. Please review custom requirements, restrictions and possible fees for delivery to Germany. Make sure your selected shipper helps you through this process. You should also ask the shipper if Germany customs will require the package to be opened for inspection.